The present invention, in some embodiments thereof, relates to an apparatus and method for depositing a material from a source or target substrate onto a receiving substrate, and more particularly, but not exclusively, to depositing a patterned material from a target substrate onto a receiving substrate.
During the manufacturing process of some products it is desired to deposit a material, such as conductors, in a patterned form onto a receiving substrate. Such products may include for example, semiconductor integrated circuits (IC), semiconductor IC packaging connections, printed circuit boards (PCB), PCB components assembly, solar photovoltaic cells (PV cells), optical biological, chemical and environment sensors and detectors, RFID antennas, OLED displays (passive or active matrix), OLED illuminations sheets, printed batteries and more.
The prior art has used one of a number of methods for laying down such materials including, evaporation, masking and etching, ink-jet writing and silk screening. One method is deposition of strips of conductor material onto a substrate from a target substrate coated with a continuous layer of the material by selectively heating the side of the layer facing the substrate with a laser.
For example, U.S. Pat. No. 6,177,151 to Chrisey et al. discloses a device including a source of pulsed laser energy, a receiving substrate and a target substrate. The target substrate comprises a laser transparent support having a back surface and a front surface. The back surface has a continuous coating that comprises a mixture of the transfer material to be deposited and a matrix material. The matrix material is a material that has the property that, when it is exposed to pulsed laser energy, some of the components of it are volatile. The source of pulsed laser energy is positioned in relation to the target substrate so that pulsed laser energy is directed through the back surface of the target substrate and through the laser-transparent support to strike the coating at a defined location with sufficient energy to volatilize the volatile material at the location with enough force to cause a portion of the coating to desorb from the location, detach from the surrounding material and lift from the surface of the support. The receiving substrate is positioned in a spaced relation to the target substrate so that the part of transfer material in the desorbed coating is deposited at a defined location on the receiving substrate.
U.S. Pat. No. 7,001,467 to Piqué et al. discloses a system using two lasers. A first laser is positioned in relation to the target substrate so that a laser beam is directed through the back surface of the target substrate and through the laser-transparent support to strike the continuous coating at a defined location with sufficient energy to remove and lift at least the non-volatile portions of the source material from the surface of the support and detach it from the surrounding material. A second laser is then positioned to strike the deposited source material to transform the source material into the material of interest, for example to serve as an electrical conductor.
In the process of the production of some products, such as crystalline solar cells, the receiving substrate is coated with a passivation layer. It is desired to create openings in the passivation layer into which the material will be deposited. The prior art has performed this in two stages. First the openings are created in the passivation layer. Then, by use of direct writing (for example, using the methods of the two previously described patents), the material is deposited into the openings in the passivation layer of the substrate. Usually, the pattern is a set of parallel lines. This type of direct writing requires precise alignment of the laser and receiving substrate since the material has to be deposited from the continuously coated substrate into the openings that have been previously formed in the passivation layer. Another option is to use material which will penetrate into the passivation layer.
US 2008/0139075 to Birrell et al. describes the use of optical lenses to focus the laser beam on the target and the receiving substrates, thereby providing precise alignment of the two. Birrell explains that since the coating on the target substrate is relatively thin, two or more depositions of the coating are required at a single position on the receiving substrate. Since the target substrate has a continuous coating, the target substrate is moved with respect to the receiving substrate so that two or more material depositions are available at the same spot. A first lens is used to review the target substrate for available coating material the target substrate. A second lens is used to review the receiving substrate for places where the substrate requires material deposition.
US 2007/0169806 to Fork et al. uses a laser based or particle beam patterning system to define contact openings through a passivation layer to expose doped portions of the underlying wafer and then uses a direct write metallization apparatus, such as an inkjet-type printing apparatus or an extrusion-type deposition apparatus to deposit contact material into each of the contact openings.
Additional background art includes U.S. Pat. No. 6,805,918 to Auyeung et al., U.S. Pat. No. 6,815,015 to Young et al., U.S. Pat. No. 7,335,555 to Gee et al, U.S. Pat. No. 6,649,861 to Duignan, U.S. Pat. No. 4,265,545 to Slaker, U.S. Pat. No. 7,046,266 to Retschke et al. US 2004/0056009 to Gross et al., U.S. Pat. No. 6,331,177 to Mummerlyn et al., U.S. Pat. No. 5,654,975 to Green et al., U.S. Pat. No. 4,701,592 to Cheung et al., U.S. Pat. No. 4,469,430 to Terashima et al., U.S. Pat. No. 4,970,196 to Kim et al., U.S. Pat. No. 5,156,938 to Foley et al. and “Scanning ND: Yag Laser System for Industrially Applicable Processing in Silicon Solar Cell Manufacturing” by Schneiderlocher, E. et al.